No abstract

IN work related to the causation of human lung cancer, some investigators, appreciating the proposed special cancer environment of the cigarette smoker, seek to support this proposition by discovery of new carcinogenic agents or adjuvant factors in cigarette smoke, to which non-smokers are not especially exposed. Thus smoke phenols (Roe, Salaman and Cohen, 1959) and bases (Wynder and Wright, 1957) have been cited as co-factors in what would essentially be carcinogenesis by smoke polycyclic hydrocarbons. The discovery of appreciable quantities of free radicals in cigarette smoke (Lyons, Gibson and Ingram, 1958) led to the proposal of their possible involvement in the carcinogenic process. This followed from various suggestions in the literature on the possible pivotal role of free radical forms in cancer production by a variety of agents (for reference see Bamford and Jenkins, 1960). A more speculative aspect, perhaps, of the free radical hypothesis is the possible sensitization of cells to the deleterious action of carcinogenic agents by free radicals through their paramagnetism, an idea related to that of Howard, Hawes and Gray (1959) who are seeking to establish whether the well-known radiosensitizing action of oxygen and nitric oxide is due to the paramagnetic property of these agents.For present purposes it was decided to attempt an estimation of the relative amounts of free radicals to which cigarette smokers and non-smokers are liable to be exposed, and to investigate any qualitative differences among such radicals which might have a bearing on their possible biological action. As regards the latter point, it seemed desirable to have an estimate of their size and stability. For these ends, the following experimental work was undertaken. EXPERIMENTALFree Radicals in general atmospheric pollution Suspected sources of general atmospheric free radicals examined were: domestic chimney smoke, vehicular exhausts and cigarette side-stream smoke.Samples of particulate exhaust products from mechanically sound petrol and diesel enges were collected in glass containers which were kept cool during the sampling. The diesel soot samples were collected at speeds of 2080, 1400 and 800 r.p.m., at 10 per cent overload from vehicle engines on a test bed.(Negligible quantities of soot were produced at reduced loads.) The petrol engine soots were collected during acceleration-deceleration and idling periods from privately owned cars. All the exhaust condensates were filtered and dried over phosphorus pentoxide. These samples were tested for the presence of free

THE first successful production of carcinomata (in the skin of mice) using cigarette tar produced by a method designed to simulate the human habit, was achieved by Wynder, Graham and Croninger (1953). These results were confirmed subsequently by the same workers and by Sugiura (1956) using the same tar which was in all cases obtained from American cigarettes. More recently, Passey, Boyland, Pratt and Hieger (1956), applying a tar prepared from American cigarettes to mice under conditions comparable to those employed by the American workers obtained a much lower incidence of tumours than the latter after the first year of painting. The London workers had two mice presenting papillomata compared with fifteen mice bearing papillomata and two epitheliomata in the American workers' experiment (Wynder, Graham andCroninger, 1953, 1955) (Chalmers, 1954), (2) intra-pulmonary injection (Beck, 1954) and (3) injection into growing embryonic implants (Lyons, Peacock and Peacock, 1956). However, recently Blacklock (1957) produced an oat-celled carcinoma in the lung of one rat of eight given intrapulmonary inoculations of a tar from proprietary filters through which human subjects had smoked.Therefore it seems, from the latter experiment, that British cigarette tar may be carcinogenic, and (from the comparative series of experiments using British and American cigarette tars) that differences in carcinogenic potency exist between these tars.Wynder and Wright (1956 and 1957) showed that in the American cigarette tars the carcinogenic factors for mice and rabbits resided mainly, though not exclusively, in the neutral fraction, and further that the 3,4-benzpyrene content was insufficient to account for the biological activity of that fraction.The present paper records investigations into the composition of the fractions of "neutral tar" from British cigarettes which immediately precede and succeed 3,4-benzpyrene on the chromatographic column, there being evidence from chemical and biological investigations of other tars and oils (see discussion) for the occurrence of carcinogenic agents in these fractions.

Injures are common in workers engaged in tactical occupations. Research suggests that the functional movement screen (FMS) may provide practitioners the ability to identify tactical athletes most at risk for injury. However, there exists controversy as to the effectiveness of the FMS as a tool for classifying injury risk. The purpose of the meta-analysis was to determine the predictive value of the FMS in determining injury risk in workers engaged in tactical occupations. We searched MEDLINE, Military & Government Collection (EBSCO), PubMed and National Institute for Occupational Safety and Health Technical Information Center databases for articles published between January 2007 and October 2017. Ten studies met the inclusion criteria. Multiple random-effects model meta-analyses were conducted, with an odds ratio as the effects metric. FMS cut-off score, occupation, injury type and sex were used as moderators for the analyses. The odds of injury were greatest for tactical athletes with FMS scores ≤14. Personnel scoring ≤14 had almost 2 times the odds of injury as compared to those scoring >14. However, the magnitude of the effects were small; thus the relationship between FMS cut scores and injury prediction does not support its use as a sole predictor of injury.